The goal of this study was to develop a new route to prepare thermally responsive polymer nanogels Poly (N-vinylcaprolactam) nanogels were prepared via inverse miniemulsion polymerization (MO) at 70 degrees C using n-hexadecane as a nonpolar continuous phase, potassium persulfate as an initiator, and N,N'-methylenebisacrylamide as a crosslinker. Sorbitan monooleate (Span 80) was used as surfactant and its influence on the polymerization kinetics and on the colloidal characteristics of the nanogels were principally investigated It was observed that the addition of a strong "lipophobe" is required to stabilize the resulting miniemulsion The nanogels were characterized in terms of morphology, size, zeta potential, and thermoproperties using transmission electron microscopy and dynamic light scattering It was observed that all the nanogels obtained collapsed when the lower critical solution temperature (LCST) was raised (C) 2010 Wiley Periodicals, Inc J Polym Sci Part A Polym Chem 48 3932-3941, 2010